Does Google Sitemap help? Before I created and submit Google Sitemaps for my websites, I asked the same question to myself. And I also did a research on the Internet. The answer was mostly positive. However, none of the information I found on the web didn’t give any hard evidence about the benefit of having a Sitemap.
I had some resistance from our web developer, as they think a website which has already been indexed by Google doesn’t need to submit Sitemap. They insisted that submitting Sitemap of a already indexed website will have nagetive impact on the website’s index. The URLs which are not in the Sitemap won’t be indexed at all. However, considering the number of pages we have on our webiste and been indexed by Google, I firmly believed that submiting Sitemap can bring some benefit to our websites’ index.
Our company has five different webistes. Gemondo is the biggest one which has more than 5,000 jewellery items listed on it. marcasites.co.uk, celticandcladdagh.co.uk, stijlstyle.com and 24karatpuredevotion.com are much smaller websites in terms of item number and page number. I used a free Sitemap generator GSiteCrawler to create Sitemap for my websites. This is particular good for generating Sitemap for big webiste with tens of thousand of pages.
I keeping on tracking the number of pages indexed through Webmaster Tools after I submit the Sitemap to Google. I can see a significant increase in the number of pages indexed one month after I submit the Sitemap.

http://www.stijlstyle.com indexed page number

http://www.24karatpuredevotion.com indexed page number
From the above statistics we can see that indexed page number increased sharply after submission. Although there’s downward trend after the sharp growth, overall the indexed page number is still a lot more than before.
Therefore, I can draw the conclusion that submitting Sitemap can definitely increase the indexed page number on Google. Some say that this is extremely good for new websites.
I didn’t include the result for Gemondo.com, since I’m still having problem with submitting the Sitemap to Webmaster tools. I will post the result on my blog when it become successful.